EP3330068B1 - Device for dewatering bulk or flowable material - Google Patents

Description

The invention relates to a device for dewatering pourable or flowable feed material, for example wood chips, by compacting it, with a housing with a casing tube in which a shaft with circumferential helices rotates about an axis of rotation, the feed material being transported and compacted through the housing and the pressate is led out of the device through openings in the jacket tube and an inner tube is provided, the inner tube is constructed from segments which have openings, the segments resting with their outer surface directly on the inner surface of the jacket tube and the openings of the segments the openings of the jacket tube, the openings of the segments having a smaller cross section than the openings of the jacket tube.

Such devices are, for example, from DE 20 2007 007 038 U1 known, which discloses the features of the preamble of claim 1, these devices usually having a feeding device, for example in the form of a shaft. Special versions are used to feed wood chips into a pulp digester in the pulp industry and are often referred to as stuffing screws in this context. There are also applications, among other things, as a feed device for cookers in the wood pulp industry. Generally, a commodity is pumped from an area of lower pressure to an area of higher pressure or vice versa. These devices therefore also serve as a pressure lock. In addition to pressing out the pressate (effluent), usually water with chemicals if necessary, the compression of the feed material also serves to create a highly compacted plug of material, which seals the inlet opening from the pressurized system of a cooker. With other devices such as MSD, a highly compressed plug of material is also created, which in this case absorbs the impregnation chemicals when it relaxes. With such devices, the high compression of the feed material with the result of high contact pressure on the inside of the screw casing results in a high level of wear on both the screw helix and the casing tube, so that such devices have to be renewed or upgraded at regular intervals. This results in high costs and longer downtimes in production. The worn housings are often renovated using build-up welding and mechanical processing. The disadvantage of this application method is that the workpiece twists and shrinks during welding This means it can no longer be inserted precisely into the casing pipe. The internal stress resulting from the heat input during welding can lead to cracks and subsequent failure of the component. Renovation is expensive and time-consuming, with the component having to be transported to a workshop for renovation. Alternatively, so-called wear shells are used, which can be replaced. These are half-shells made of wear-resistant material, which are fitted into it after the casing tube has been dismantled and thus form an inner tube. These are very difficult to manufacture and there are often problems with fit. Such wear shells are usually more expensive than renovation through build-up welding.

The aim of the invention is to provide a device that is significantly more cost-effective and avoids the above disadvantages.

This goal is achieved by a device according to claim 1.

By constructing the inner tube from segments, the replaceable parts become smaller and can be transported more easily. Because the segments rest directly on the inner surface of the casing tube, these parts are supported over the entire surface and can therefore also be manufactured with very small wall thicknesses. Casing pipe and segments can also be made from different materials, which means that the casing pipe can absorb the forces and the segments can be made of a hard, brittle and therefore wear-resistant material. By being designed as a cast or sintered part, the segments can remain largely unprocessed. This eliminates the need for large-scale, cost-intensive processing of both the external and internal surfaces. The openings can also be cast, which means that subsequent, complex drilling, especially cutting drilling, becomes unnecessary. This also makes it possible to use harder materials that can no longer be processed using machining processes. By matching the openings of the segments with the openings of the casing pipe, optimal drainage is achieved.

A favorable embodiment of the invention is characterized in that the casing tube is cylindrical, although it can alternatively be conical. In this way, the device can be conveniently adapted to the needs of production and the screw required for it.

A favorable development of the invention is characterized in that the inner tube consists of at least 4, preferably 6 - 8 segments in the circumferential direction. This means that areas that are less worn can be left in place and only areas that are more heavily worn can be replaced.

An advantageous embodiment of the invention is characterized in that the inner tube consists of at least 2, preferably 3 - 4 up to 6 segments in the longitudinal direction, corresponding to the direction of the axis of rotation. On the one hand, this makes assembly much easier, but on the other hand, little worn areas can be left and only more heavily worn areas, especially in the area of high compression at the end, can be replaced.

A favorable development of the invention is characterized in that the openings of the segments expand conically towards the outer surface. This means that blockages in the openings can be largely avoided.

A further favorable embodiment of the invention is characterized in that the segments each have a groove in the longitudinal direction. These grooves can be used specifically to prevent the feed material from rotating.

An alternative embodiment of the invention is characterized in that the segments each have a particularly integrated strip in the longitudinal direction. These bars can also be used to prevent the feed material from rotating.

In particular, the design made of cast or sintered material enables cost-effective production and allows for no further processing. This means that the drainage openings can also be cast, eliminating the need for time-consuming drilling.

• Fig. 1 den grundsätzlichen Aufbau einer gattungsmäßigen Entwässerungsvorrichtung,
• Fig. 2 das Gehäuse einer erfindungsgemäßen Vorrichtung mit Innenrohr,
• Fig. 3 eine Halbschale der erfindungsgemäßen Vorrichtung,
• Fig. 4 eine Halbschale mit Darstellung der erfindungsgemäßen Segmente und deren Befestigung
• Fig. 5 eine Variante eines erfindungsgemäßen Segments,
• Fig. 6 eine weitere Variante eines erfindungsgemäßen Segments
• Fig. 7 eine zusätzliche Variante eines erfindungsgemäßen Segments

darstellt.The invention will now be described by way of example with reference to the drawings, where:

• Fig. 1 the basic structure of a generic drainage device,
• Fig. 2 the housing of a device according to the invention with an inner tube,
• Fig. 3 a half-shell of the device according to the invention,
• Fig. 4 a half-shell showing the segments according to the invention and their attachment
• Fig. 5 a variant of a segment according to the invention,
• Fig. 6 another variant of a segment according to the invention
• Fig. 7 an additional variant of a segment according to the invention

represents.

In Fig. 1 a drainage device 1 with a stuffing screw 2 and a drive 3 is shown. The drive 3 has a drive motor 4, a gearbox 5, a clutch 6, for example a high-speed clutch, a further clutch 7, for example a low-speed clutch, and protective devices 8. The stuffing screw 2 consists of a feed shaft 9, the housing 10 with a discharge chamber 11, and the screw 12 with spirals 13. The housing 10 can be cylindrical as shown, but can also be designed to be tapered. The housing 10 of the stuffing screw 2 is attached to a container 14, which in the case of use in the pulp industry can be a pulp digester, the container generally having a different pressure level, but the substances can also have a different physical state. The stuffing screw then also serves as a pressure lock. The material placed in the feed shaft, for example wood chips, but also annual plants, straw, bagasse or the like, is guided through the screw spirals 13 of the screw 12 into the housing 10 and pressed through it, with liquid, usually water, which can also be mixed with chemicals , flows into the drain chamber 11 and is removed from there and, if necessary, recycled. With other devices such as MSD, a highly compressed plug of material is also created, which in this case absorbs the impregnation chemicals when it relaxes. Due to the high compression of the feed material, high wear occurs on the inside of the housing 10, so that these housings often have to be replaced or armored. One possibility is to remove the housing and make it usable again in a workshop through build-up welding and subsequent mechanical processing. This means that this part will not be available to the system operator as an emergency spare part for a long period of time. As an alternative, replaceable wear shells can be used. However, these have to be manufactured very precisely, which often results in problems with the fit.

Fig. 2 shows a housing 10 according to the invention, which consists of an upper half-shell 15 and a lower half-shell 16. These have drainage openings 17, which can be arranged in groups as shown. The half-shells 15, 16 have flanges 18 and 18 'at their ends, with which the housing 10 is fastened to the feed shaft 9 on one side and to the container 14 on the other side. The two half-shells 15, 16 are held together with a number of screws 19. Segments 21, 22 are arranged within the half-shells 15, 16. Additional screws 20 are used to fasten these segments 21, 22 to the housing 10. All segments 21, 22 together form an inner tube in the housing 10. Shown here are 6 segments 21, 22 distributed around the circumference. However, depending on the diameter of the housing 10, fewer or more segments can be distributed around the circumference. The outer surface of the segments 21, 22 rests directly, ie without a gap, on the inner surface of the half-shells 15, 16 of the housing 10.

In Fig. 3 the lower half-shell 16 is shown. It has flanges 18, 18' at the ends. The individual segments 21, 22 have openings 23 for fastening using screws 20. You can see that different segments can be used here. The segments 21 have a groove 24 along their length, which serves to prevent substances from rotating. In addition to segments 21, there are also segments 22 that do not have a groove. The number of segments 21 with groove 24 and segments 22 is selected based on the drainage behavior, but also the caking and thus carrying properties of the feed material. The use of segments 21 and 22 makes it possible to adapt the dewatering and transport of the feed material accordingly. As an alternative to segments with a groove, segments 22' (see Fig. 7 ) can be used with strips to prevent the feed material from being carried away. Three segments 21 and 22 arranged in a row are shown here in the longitudinal direction of the housing 10. Depending on the length of the housing 10, there can of course also be several segments 21, 22 in the longitudinal direction, ie in the direction of the axis the snail. It is important that the openings 25 of the segments 21, 22 correspond directly to the openings 17 of the half-shells 15, 16, that is, each opening 25 in a segment 21, 22 is assigned an opening 17 in a half-shell 15, 16 of the housing 10. This is achieved, among other things, by fastening using screws 20. The screws 20 are inserted from the inside, ie the interior of the cylinder formed by the segments 21, 22, and screwed on the outside using nuts. As a result, a thread is not required in either the segments 21, 22 or the half-shells 15, 16 of the housing 10. This means that much harder materials can also be used for the segments 21, 22, since no processing is required. The heads of the screws 20 are, for example, elongated with a spherical cap so that they are always in the correct position in the correspondingly shaped openings 23. The screws 20 can also have recesses such as slots in the heads that are arranged on the inner (cylinder) surface of the segments 21, 22, which then form a plane due to the wear of the segments and the raised parts of the screw heads can be used as wear marks, which provide an indication of the necessary replacement of the segments 21, 22. The segments 21, 22 are cast from wear-resistant material, whereby all openings 25 can be manufactured in a simple manner without subsequent mechanical processing. The openings 25 can also be made conical very easily and do not have to be designed as stepped bores, which require frequent tool changes during production. Alternatively, the segments can also be sintered from wear-resistant material, which also offers the possibility of incorporating the openings 25 in a simple manner. By designing the segments 21, 22 as cast or sintered parts, significantly harder materials can be used that can no longer be processed with conventional cutting tools such as drills.

In order to save further mechanical processing, contact surfaces 26 are created only on the long sides of the edges of the segments 21, 22 near the ends of the segments 21, 22, which must be slightly processed in order to ensure an exact fit of the individual segments 21, 22 . The arrangement of several segments 21, 22 in the longitudinal direction also makes it possible to replace only the segments with the greatest wear. With this type of inner lining of the housing, repairs can be carried out easily and in a short time on site.

Fig. 4 shows the simple assembly using the example of a segment 21. Here, three segments 21 with grooves 24 are shown on a lower half-shell 16, which results in 6 segments over the entire circumference of the housing 10. In the last segment 21 you can see the holes 25, which are arranged above the corresponding holes 17 in the half-shell 16. Furthermore, the fastening screws 20 and the machined contact surfaces 26 can be seen. The segments 21 (and also 22) are not processed on the end faces. The outer surfaces and the inner surfaces are also not processed, since the grooves 24 can also be cast.

In Fig. 5, 6 and Fig. 7 Segments 21, 22 and 22' according to the invention are shown. These have openings 23 for the fastening screws 20, drainage openings 25 and contact surfaces 26. The difference between segments 21 and 22 is that segment 21 also has a groove 24, which is intended to prevent the feed material from rotating. In Fig. 7 a variant of a segment 22 'is shown, in which a strip 27 is provided instead of a groove 24. This bar is also intended to prevent the feed material from rotating. This strip can be easily integrated into a cast or sintered part and manufactured in one piece. This means that disadvantages caused by screwed-in strips can be avoided. There is also no need for post-processing of the segment using, for example, machining processes (grinding a groove, drilling screw holes), which means that harder materials can also be used.

The invention is not limited by the drawings, in which slightly conical housings are shown. For example, cylindrical housings and thus cylindrical segments can also be used. With larger diameters, the housing could also consist of three or four parts.

Claims (9)

1. Device for dewatering feedstock that is pourable or free-flowing, for example wood chips, by compressing it, comprising a housing (10) with a shell pipe (15, 16) in which a shaft with flights (13) running round its circumference rotates round an axis of rotation, where the feedstock is transported through the housing (10) and compressed and the pressate is conveyed out of the device through holes (17) in the shell pipe (15, 16), and where an internal pipe is provided, the internal pipe is built up from segments (21, 22) with holes (25), where the outer surface of the segments (21, 22) rests directly on the inner surface of the shell pipe (15, 16) and the holes (25) in the segments overlay the holes (17) in the shell pipe (15, 16), where the holes (25) in the segments (21, 22) have a smaller cross-section than the holes (17) in the shell pipe (15, 16), characterized in that each hole (25) in the segments (21, 22) is assigned to a hole (17) in the shell pipe (15, 16), wherein the holes (25) of the segments (21, 22) match up directly with the holes (17), i.e. each hole (25) in a segment (21, 22) is assigned to a hole (17) in the shell pipe (15, 16), and where the segments (21, 22) are made of wear-resistant cast or sintered material.
2. Device according to Claim 1, characterized in that the shell pipe (15, 16) is cylindrical.
3. Device according to Claim 1, characterized in that the shell pipe (15, 16) is conical.
4. Device according to one of Claims 1 to 3, characterized in that the internal pipe comprises at least 4, preferably 6-8 segments (21, 22) in circumferential direction.
5. Device according to one of Claims 1 to 4, characterized in that the internal pipe comprises at least 2, preferably 3-4 and up to 6 segments (21, 22) in longitudinal direction in accordance with the direction of the axis of rotation.
6. Device according to Claims 1 to 5, characterized by the holes (25) in the segments (21, 22) becoming wider conically towards the outer surface.
7. Device according to one of Claims 1 to 6, characterized in that the segments (21, 22) each have a groove (24) in longitudinal direction.
8. Device according to one of Claims 1 to 6, characterized in that the segments (21, 22) each have a strip (27) in longitudinal direction, in particular an integrated strip.
9. Device according to one of Claims 1 to 8, characterized in that the segments (21, 22) have openings (23) for fastening the segments (21, 22) with screws (20).

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